Figure 1-7.wall and column foundations.
Figure 1-8.Plan and section of a typical spread footing.
ground. The foundation wall, contrary to its name, may
be a column or a pedestal instead of a wall. But, when
it is a wall, it forms what is known as a continuous
foundation. Figure 1-7 shows common types of wall
and column foundations.
The continuous foundation is the type of foundation
that is most commonly used for small buildings. The size
of the footing and the thickness of the foundation wall
are specified on the basis of the type of soil at the site.
Most building codes also require that the bottom of the
footing be horizontal and that any slopes be
compensated for by stepping the bottom of the footing.
Another type of foundation
foundation. A grade beam is a
is the grade-beam
Figure 1-9.Plan and section of a mat foundation.
beam located at grade level around the entire perimeter
of a building, and it is supported by a series of concrete
piers extending into undisturbed soil. The building loads
are supported by the grade beam, which distributes the
load to the piers. The piers then distribute the load to the
A spread foundation, such as the one shown in
figure 1-8, is often required where heavy concentrated
loads from columns, girders, or roof trusses are located.
This type of foundation may be located under isolated
columns or at intervals along a wall where the
concentrated loads occur. Spread footings are generally
reinforced with steel. They may be flat, stepped, or
sloped, such as shown in figure 1-7.
Figure 1-9 shows the plan and section of a typical
mat foundation. In this type of foundation, a heavily
reinforced concrete slab extends under the entire
building and distributes the total building load over the
entire site. This minimizes problems created by unequal
settlement when the subsoil conditions are uneven. The
mat foundation is often referred to as a floating
Piles include many different types and materials.
The following text discusses the more common types.